Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/38—Torches, e.g. for brazing or heating
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/46—Details
  • F23D14/62—Mixing devices; Mixing tubes
  • F23D14/64—Mixing devices; Mixing tubes with injectors

Definitions

• the present invention relates to a burner / generator of hot air with internal ignition.
• gas burners of intrinsically cold nozzle type capable of performing external combustion of a gas mixture at high speed.
• burners of this type frequently apply to the low temperature heating of plastic film, for example polyethylene film, with a view to their retraction by means of a gaseous flow coming from the combustion of a combustible gas.
• a gaseous flow coming from the combustion of a combustible gas such as propane and air.
• the burner must therefore be designed to produce a gas flow having a temperature of the order of 120 ° to 540 ° C. at a predetermined distance from the burner (distance at which the plastic film to treat must be arranged).
• the temperature must be relatively homogeneous and the gas stream free of burning material, so as to avoid any possibility of burning, scorching and blistering of the film.
• a burner comprising an injection device capable of producing a flow of combustible gas mixture to high speed and to inject this flow into a tabular shaped burner head successively comprising:
• a pressure recovery chamber having, in the plane of symmetry of the head, a divergent shape and inside which the gaseous mixture coming from the injection device develops in a fan configuration
• diffusion means that may comprise a grid at the same one set of two grids, of substantially semicylindrical shape fixed inside the head at the junction of the two chambers, these diffusion means forming a convex partition, oriented parallel to said edges, in said plane of symmetry, and whose concavity is oriented towards the inside of the pressure recovery chamber.
• the diffusion means can be made from a mesh or a perforated sheet.
• the tubular housing of the candle forms a cavity generating a turbulent regime of the gas flow emitted by the perforations of the grid.
• a permanent self-sustaining combustion of the gas flow can be established at this cavity, causing a heating of the wall of the ignition chamber, which is contrary to the purpose.
• an ignition device involving an ignition cavity external to the ignition chamber, and communicating with it through a reduced section passage orifice provided in the wall the ignition chamber substantially to the right of the front region of the gate, the section of this orifice being provided sufficiently small to ensure that the disturbances of the gaseous mixture flow at this orifice can not generate a focus of Parasite combustion self-maintenance likely to heat the wall of the ignition chamber.
• a major problem that must be solved in the design of a direct ignition device is that of the voltage and energy of the electrical pulses that should be applied to the electrodes d ignition, to effectively ignite the gas mixture flowing at high speed inside the burner.
• the gap between the electrodes must be relatively large. This voltage and this instantaneous energy must therefore be relatively high so that it is appropriate to use, on the one hand, a sufficiently powerful generator and, on the other hand, an electrical connection between the generator and the electrodes which is particularly well isolated so as to avoid online losses or disruptions.
• the object of the invention is therefore more particularly to eliminate all these disadvantages.
• a cold nozzle gas burner of the aforesaid type in which single or multiple diffusion means comprise a central orifice into which an ignition chimney extends which extends axially inside the chamber. pressure recovery, this ignition chimney defining an ignition chamber provided with ignition electrodes in communication with the burner pressure recovery chamber through a calibrated orifice.
• the spark generated between the ignition electrodes causes the gaseous mixture to ignite without igniting inside the ignition chamber, and a combustion that propagates axially to the combustion chamber of the burner thus causing ignition of the burner.
• the ignition chimney is constantly scanned and cooled by the gas mixture circulating in the burner pressure recovery chamber.
• this ignition chimney is not the seat of a significant rise in temperature.
• the tabular ignition chamber may be extended at one of its ends by a minimum cross-section chimney to prevent any backfire but nevertheless allow the propagation of the gas mixture during combustion for ignition , and the other end may be closed by a sleeve of insulating material provided with a coaxial ignition electrode.
• This electrode cooperates with at least one annular portion of the body made of an electrically conductive material which constitutes a second ignition electrode surrounding the first.
• the burner previously described may be designed so as to be equipped with an extension consisting of a tabular element, possibly telescopic, which can be inserted between the nozzle of the injection device and the burner head.
• the driver who passes through the extension to connect the output of the electrical generator to the ignition electrode disposed in the ignition chamber constitutes with said extension a capacitor whose capacitance is a function of the length of the extension and the layout of the driver inside said extension.
• This capacitor has the disadvantage of absorbing a large fraction of the electric charge delivered by the electric generator at the moment of ignition. The charge applied to the ignition electrode is thus weakened.
• a third problem results from the fact that the gases propelled at high speed by the injection pipe do not mix homogeneously inside the extender.
• This heterogeneity is itself a function of the length of the extender.
• the use of deflectors intended to create disturbances in the gas flow to improve this homogeneity nevertheless has the disadvantage of slowing the flow, which is contrary to the desired effect in a high-speed burner.
• the invention therefore also aims to solve these problems.
• this additional grid may be permanently disposed within the pressure recovery chamber, against or in the immediate vicinity of the diffusion means.
• this additional grid may be arranged between the two diffusion grids.
• the invention proposes to use a rigid electrical conductor having a portion that extends obliquely between the two connecting members respectively located at the ends of the extension. This electrical conductor comes to connect:
• the connector preferably forming a bend, so as to reach a region symmetrical to that of the connection to the conducting washer before return to the electrical connection finger.
• the distance separating the wall of the extender from the ends of the oblique portion of the electrical conductor must be greater than a determined distance so as to avoid the formation of parasitic electric arcs.
• the capacitance of the capacitor formed between the conductor and the extender remains in the limits of the face, owing to the performance of the ignition device previously described, and the oblique portion of the conductor. causes a progressive disruption gas flow over the entire length of the extender, and over its entire section.
• This disturbance which makes it possible to obtain a homogeneous gaseous mixture, does not, however, cause a noticeable slowing down of the gaseous flow, and this, because of its progressivity along the oblique portion of the conductor.
• the electrical conductor may be made of at least two rigid elements, one of these two elements being tubular while the other consists of a cylindrical rod which engages tightly in the element tubular. These two elements have at least partially the same oblique.
• Figure 1 is a vertical sectional view of a cold nozzle type high speed short burner
• FIG. 2 is a schematic section illustrating the operating principle of the burner shown in Figure 1-f- Figure 3 is a schematic perspective view of the burner head;
• Figure 4 is a section on a larger scale of the burner head shown in Figure 1;
• FIG 5 is a partial sectional view of an alternative embodiment of the burner of Figure 1 equipped with an extender
• Figure 6 is a partial section of the technical variants of the extension detent system and the ignition electrode connection
• Figure 7 is a schematic partial section of a telescopic extension.
• the burner according to the invention comprises an injection device 1 adapted to transmit to the burner head 2, a combustible gas mixture stream.
• This injection device 1 is more particularly involved:
• a tubing 3 formed in two sections, namely a convergent posterior section 4 and a substantially divergent anterior section 5; an injection nozzle 6 mounted in the convergent section 4, this nozzle 6 being connected to a source of flammable gas having a pressure of the order of 1 to 4 bars, and
• the burner head 2 of tabular form, consists of two electrically conductive metal parts, which successively delimit a pressure recovery chamber 10 which connects to the tubing and an ignition chamber 11 which opens at the same time. outdoors.
• the pressure recovery chamber 10 has beyond its connection zone to the pipe 3, a flared shape delimited by two converging walls 12, 13, of increasing width and two diverging side walls 14, 15 of decreasing width. As can be seen in FIGS. 2 and 3, the front edges 16, 17 of the two convergent walls 12, 13 have coaxial circular shapes.
• the ignition chamber 11 has a shape also flared. However, in this example, it is delimited by two parallel walls 18, 19 which extend the two converging walls 12, 13, and two diverging side walls 20, 21 which extend the side walls 14, 15, respectively in the same orientations.
• the front edges 22, 23 of the two walls 18, 19 are circular and extend coaxially with the borders 16, 17.
• a double diffusion grid 24 which consists of two pieces of perforated sheet having the shape of a toric sector of substantially semicylindrical section, and whose large radius of curvature corresponds substantially to that of the anterior edges 16, 17 of the converging walls 12, 13.
• the walls 18 and 19 of the ignition chamber 11 are extended by two circular deflectors 30, 31 which converge substantially towards one another and have two coaxial respective edges 32, 33 forming between them a passage space of width less than the width of the lateral sides 20, 21 of the ignition chamber 11.
• the speed of the gas mixture is slightly reduced while it develops in a fan configuration.
• a relatively homogeneous pressure zone is formed, due to a conversion of the kinetic energy of the gas flows.
• these jets are oriented axially while in the lateral parts, they are substantially radial and abut on the walls 18, 19 and on the baffles 30, 31.
• the speed of the gas flow is not homogeneous, which should, in principle, lead to a heterogeneity of the flame.
• deflectors 30, 31 which serve to deflect the fuel mixture flow zones from the side portions of the grid 24 and to make them slightly converge towards the central region of the gas flow.
• this ignition device involves a cylindrical ignition chamber 43 which extends coaxially with the head 2 of the burner inside the pressure recovery chamber 10 via a ignition chimney 44 which passes through the double perforated grid 24 at its center and opens into the ignition chamber 11 while in the other end of the ignition chamber, engages a tabular sleeve.
• a cylindrical ignition electrode 42 having three successive steps 42 ', 42 ", 42'" corresponding to the steps of said bore is provided.
• the staggering 42 'of the smaller diameter electrode 42 protrudes outside the socket 41 within an ignition chamber 43.
• the staging 42 '' 'of larger diameter extends outside the sleeve 41 to the level of the connection between the pipe 3 and the head 2 of the burner.
• the ignition assembly 40 electrically conductive comprises: a first tubular portion 44 of small passage section, the ignition chimney, one end of which engages through the double gate 24 and the other side a second tubular portion 45 of larger internal closed section, on the side opposite the chimney, by the insulating sleeve 41 of the electrode 42.
• the ignition assembly 40 is in electrical contact with two electrically conductive parts of the head 2 of the burner, on the one hand, via the double gate 24 and, on the other hand, by a holding piece 47 electrically conductive which extends radially in the pressure recovery chamber 10.
• the head 2 of the burner fits on the end of the pipe 3 by means of an assembly to ensure both a seal and a goodconnection _electric, _entent- that- the-tubing- 3- is electrically connected to the ground of a piezoelectric generator housed in a handle P integral with said manifold 13.
• the actuation of the piezoelectric generator is provided by a trigger G equipping the handle P.
• This assembly involves three successive coaxial grooves 48, 49, 50 axially offset, provided in the interlocking zone of the pipe 3, two O-rings 51, 52 of resilient material, respectively disposed in the first 48 and the third groove 50 and a metal blade 53 retaining resiliently deformable, whose curved end 54 is intended to engage in the central groove 49, the metal blade being secured to the burner head.
• This arrangement makes it possible to obtain a rapid tight assembly despite manufacturing tolerances of the head 2 and of the pipe 3, a good electrical contact thanks to the tongue 53 and to the zones of contact between the head 2 and the pipe 3, and a seal thanks to the O-ring 52 (the O-ring 51 essentially providing a guiding and retaining role).
• the piezoelectric generator is also connected to the ignition electrode 42 by means of an electrical conductor wire 63 and a connector located at the interlocking zone of the tubing 3.
• this connector uses an insulating collector support 55 in the form of a floor tubular sleeve, made of insulating material, comprising a first step 56 which fits into the tubing 3 and a second step 57 of external diameter. more important which has an inner surface forming an annular groove 58.
• the length of the protruding portion of the electrode 42 is determined so that, in the assembled position of the head 2 on the tubing 3, the rectilinear strand 61 of the spring 60 engages in a radial groove 62 formed in the end of the electrode 42 and remains applied in the bottom of this throat
• the assembly thus forming a rotating collector.
• the end of the electrode may comprise two radial grooves at 90 ° to each other).
• a variant of this construction Figure 6 is to replace the aforesaid spring 60 by the spring 60 'and the washer 60 "having an axial maneuvering shape 60'" connected to its peripheral portion by one or more connecting arms.
• This form of maneuver engages in or around the opposite form 62 'of the electrode 74' in order to be able to drive the washer in rotation.
• the piezoelectric generator When the piezoelectric generator is actuated via trigger G, the generated electrical pulse is applied to electrode 42 and ignition assembly 40 which acts as a second electrode.
• This arrangement also makes it possible to rotate the head 2 of the burner with respect to the tubing 3 without causing malfunction of the burner or its ignition system.
• the burner / hot air generator may comprise a tabular extender 70 interposed between the anterior end of the tubing 3 and the head 2 of the burner.
• a sieve is disposed at the same location as the grate-having-cut-oblong-in the pressure recovery chamber. or between the two grids.
• This GS screen comprises a central orifice through which the chimney 44 passes.
• this extension 70 consists of a rigid tube, optionally bent having, on one side, a female assembly profile PF of a type similar to that used in the burner head.
• this female assembly profile may comprise, according to FIG. 6, a detent comprising a ball 71 retained inside a conical bore 72 by an elastic ring. 73, so that it can partially engage in the central groove 49 of the end of the tubing 3.
• the extension 70 is provided, at this female assembly profile, with a coaxial electrical contact finger 74 mounted on a support made of electrically insulating material 75 fixed by means of the support 47 inside the extension 70 at the base of the assembly profile PF.
• This electric contact finger 74 comprises in a manner analogous to that of the electrode 42, two radial radial grooves 76 intended to receive the radial rectilinear strand 61 of the spring 60.
• the front end of the extension intended to receive the head 2 of the burner has a male coupling profile PM identical to that provided at the end of the pipe 3 and which will not be described again.
• the electric diffusion washer 59 'equipping this male assembly profile PM is then connected to the electrical contact finger 74 via an electrically conductive connecting rod 77.
• This connecting rod has au _d_elà_.die _sa_çennexioji_à _the -rondelle - a edge-59- - straight -which -s ⁇ extends obliquely relative to the longitudinal axis of the extender.
• the two ends of this section are symmetrical with respect to a midpoint located on said longitudinal axis.
• the end is connected to the electrical contact finger through a portion comprising a substantially radial segment and two bent ends.
• the extension may be bent and / or extendable telescopically.
• the connecting lead wire 77 may be made in a spiral with shape memory materials, the diameter of the turns being smaller than the inside diameter of the extension.
• the extension consists of two cylindrical tubular elements 81, 82 of slightly different diameter which fit into each other telescopically.
• connection device similar to that described with reference to FIG. 5 and which comprises a tubular sleeve 83 made of electrically insulating material, which fits partially in the element 81.
• This tabular sleeve 83 has a bore recess 84 against which is disposed an electrically-conductive washer-83-provided a -pate ⁇ connection 86 projecting inwardly.
• This connection lug has a hole through which a fixing screw is screwed into a electrical socket 87 which engages an electrically conductive connection tube 88.
• This sleeve 87 is disposed within a sheath 89 of electrically insulating material secured to the sleeve 83 by a spacer.
• a rotary connection member comprising an annular element 90 in contact with the washer 85 and a rectilinear element 91 provided with a central embossing which connects two diametrically opposite points of the annular element 90.
• Maintaining this annular element 90 in contact with the washer 85 is provided by means of a ring 92 of electrically insulating material which fits into the tubular sleeve 83.
• the rectilinear element 91 is intended to bear against the anterior face of the electrode 42 of the burner head. Nevertheless, in this case, instead of engaging in the radial groove 62 according to FIG. 4, it engages in spaces between axially projecting studs provided on the front face of a tubular sleeve MT in which the end of the electrode 42 engages.
• the sleeve MT may comprise five studs T uniformly distributed over its circumference.
• the rectilinear connection tube 88 extends obliquely with respect to the longitudinal axis of the extension.
• This tube 88 extends to the other end of the element 81. At this end, it is held in position in the central region of the tubular element 8-1- through a support -radial 93-made-in-a-material -electrically insulating integral with an insulating sleeve 94 partially engaged in the element 81.
• the end of the tubular element 82 located opposite the interlocking zone encloses a contact finger 95 similar to the finger 76 previously described, mounted on a support 96 made of electrically insulating material, and provided with two radial grooves. cross intended to receive the straight radial strand 61 of the spring 60 equipping the end of the pipe 3.
• the contact finger 95 comprises a cylindrical cavity in which engages an electrically electric rod 97.
• This rod 97 comprises, at the outlet of the cavity, a first elbow 98 and then a substantially radial portion 99 which extends to reach a region situated at a determined distance D from the wall of the tubular element 82.
• the rod 97 then has a second bend 100 which extends obliquely with respect to the longitudinal axis of the extension, to be introduced into the electrical connection tube 88 (the oblicity of the tube 88 being substantially equal to the obliquity of the rod 97).

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gas Burners (AREA)

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• 2005
  • 2005-10-28 CN CN2005800519351A patent/CN101297159B/zh not_active Expired - Lifetime
  • 2005-10-28 AT AT05815272T patent/ATE515666T1/de not_active IP Right Cessation
  • 2005-10-28 EP EP05815272A patent/EP1941207B1/de not_active Expired - Lifetime
  • 2005-10-28 US US12/091,928 patent/US8678816B2/en active Active
  • 2005-10-28 WO PCT/FR2005/002720 patent/WO2007048886A1/fr not_active Ceased

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